Since about the early 1960's considerable work has been done toward developing machines which will roll large bales of hay or other fodder, containing from about 1,000 pounds (about 450 kgs) to about 1,200 pounds (about 550 kgs). Such a bale is about 5 feet (1.5 m) in length and diameter. The first such machine was disclosed in Avery U.S. Pat. No. 3,110,145, which rolls such bales in contact with the ground.
More recent developments have taken the form of balers which have a frame with a floor provided with fodder conveyor chains or belts, with a conventional fodder pickup head at the front of the frame to feed fodder off the ground onto the conveyor. Fodder moved rearwardly by the conveyor is picked up by a forwardly moving run of bale rolling chains with cross raddles which are above the floor, with the baling raddle chains biased to minimize the length of the baling run which can expand as a bale increases in size. In principle, such balers are like an Avery baler, rolling the bale on a floor conveyor instead of on the ground. Typical of such balers is the one disclosed in Blanshine et al. U.S. Pat. No. 3,901,007.
Initially it was believed desirable to roll such bales as densely as possible, both to get the largest quantity of fodder into a bale of given size and to make the bale as weatherproof as possible. More recently it has been learned that such bales should have a relatively loose core for air circulation with a more densely packed peripheral portion to shed water and also provide the bale with a relatively rigid outer shell. Apparatus for rolling a "soft core" bale is disclosed in Kampman et al. U.S. Pat. No. 4,103,475.